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us-gaap_AccumulatedDepreciationDepletionAndAmortizationPropertyPlantAndEquipment Less accumulated depreciation Bank premises and equipment, net us-gaap_PaymentsForProceedsFromLoansAndLeases Net increase in loans Property, plant, and equipment Net of allowance for loan loss us-gaap_PaymentsToAcquireFederalHomeLoanBankStock Purchase of FHLB Stock us-gaap_RelatedPartyDepositLiabilities Related Party Deposit Liabilities Net increase in demand deposits and savings accounts The net cash inflow (outflow) in the total of all savings account deposits, which may include passbook, statement savings accounts and money-market deposit accounts (MMDAs) and all demand deposits, including checking and negotiable order of withdrawal (NOW) accounts, classified as cash flows from financing activities. SEC Schedule, 12-09, Reserve, Off-balance Sheet Activity [Member] CASH FLOWS FROM INVESTING ACTIVITIES: Available-for-sale securities, fair market value Securities - available for sale Fair Value Earnings Per Share [Text Block] Equity Securities Securities - equity investments Equity Securities, FV-NI (Decrease) increase in other liabilities Investment in bank subsidiary Equity in undistributed net income of subsidiary Increase (decrease) in interest payable and other liabilities us-gaap_RelatedPartyTransactionAmountsOfTransaction Related Party Transaction, Amounts of Transaction Investments in limited partnerships Related Party Transactions Disclosure [Text Block] Income before equity in undistributed income of subsidiary Net income before provision for income taxes Schedule of Related Party Transactions [Table Text Block] Total provision for income taxes Income tax benefit Other real estate owned Other real estate owned us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount Defined Contribution Plan, Employer Discretionary Contribution Amount us-gaap_LeaseAndRentalExpense Operating Leases, Rent Expense, Total Cash us-gaap_CashAndCashEquivalentsAtCarryingValue Cash and cash equivalents CASH AND CASH EQUIVALENTS, beginning of period CASH AND CASH EQUIVALENTS, end of period Salaries and employee benefits Cash and due from banks us-gaap_AllocatedShareBasedCompensationExpense Allocated Share-based Compensation Expense, Total SBA Pool [Member] Securities classified as SBA Pools. ovly_FinancingReceivableModificationsNumberOfContractsHeld Financing Receivable, Modifications, Number of Contracts Held Number of financing receivables held that have been modified by troubled debt restructurings. Individually evaluated for impairment us-gaap_FinancingReceivableIndividuallyEvaluatedForImpairment Collectively evaluated for impairment us-gaap_FinancingReceivableCollectivelyEvaluatedForImpairment Legal expense Individually evaluated for impairment Residential Real Estate and Other Consumer Loans [Member] Loans classified as residential real estate and other consumer loans. Collectively evaluated for impairment ovly_LoansAndLeasesReceivableGrossCarryingAmountAsPercentageOfTotalLoans Loans and Leases Receivable, Gross Carrying Amount As Percentage of Total Loans Represents the percentage of total loans segregated by class of loan portfolio. Amendment Flag Agriculture [Member] Loans classified as agriculture. 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New Accounting Pronouncements, Policy [Policy Text Block] ovly_UnderwritingStandardsLoanToValuePercentage Underwriting Standards, Loan to Value Percentage Represents the loan-to-value percentage as per the underwriting standards. ovly_FinancingReceivableModificationsPeriodContractuallyPastDueForLoanToBeConsideredInPaymentDefault Financing Receivable Modifications, Period Contractually Past Due for Loan to Be Considered in Payment Default Represents the period during which a loan is contractually past due to be considered in payment default under the modified terms. Restricted stock forfeited ovly_UnderwritingStandardsTotalDebtRatio Underwriting Standards, Total Debt Ratio Represents the total debt ratio as per the underwriting standards. us-gaap_RestrictedInvestmentsAtFairValue Restricted equity securities ovly_LoansAndLeasesReceivableMinimumCashCollateralPercent Loans and Leases Receivable, Minimum Cash Collateral Percent The percentage of the loan amount for which cash collateral must be equal to or greater than in order for the loan to properly margined. Reclassification, Policy [Policy Text Block] us-gaap_GainLossOnSaleOfPropertyPlantEquipment Gain on sale of premises and equipment us-gaap_SharesOutstanding Balances (in shares) Balances (in shares) Common stock, shares outstanding (in shares) ovly_FinancingReceivableRatingExampleDisbursementToUnsecuredCreditorsByIllusoryCompanyInLiquidationPercentage Financing Receivable, Rating Example Disbursement to Unsecured Creditors by Illusory Company in Liquidation, Percentage The percentage of disbursement to unsecured creditors by an illusory company in liquidation in order to explain the proper use of the doubtful category. Allowance for Credit Losses on Financing Receivables [Table Text Block] Gain on sale of OREO Gain on sale of OREO property Decrease (increase) in other assets Increase in other assets Current Fiscal Year End Date us-gaap_IncreaseDecreaseInDeferredCharges Decrease in deferred fees/costs, net Recoveries Gains on sales and calls of securities Interest income receivable on loans Document Fiscal Period Focus Interest income receivable on investments Document Fiscal Year Focus us-gaap_EquitySecuritiesFvNiRealizedGainLoss Equity Securities, FV-NI, Realized Gain (Loss), Total Document Period End Date Tier I capital (to Average Assets), Ratio Tier I capital (to Average Assets), Adequately capitalized threshold, Ratio Tier One Leverage Capital Required for Capital Adequacy to Average Assets Entity Emerging Growth Company Tier I capital (to Average Assets), To be well capitalized under prompt corrective action provisions, Ratio Document Type ovly_FinancingReceivableRatingExamplePercentageOfLoansClassifiedInRatingCategory Financing Receivable Rating Example, Percentage of Loans Classified in Rating Category The percentage of loans classified in rating category depending upon the probability of loan collection in the example used to explain the proper use of the doubtful category. Total capital (to Risk- Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio Entity Small Business Shareholder cash dividends paid Land Loans [Member] Loan to finance the purchase of land. Document Information [Line Items] Mortgage Loans [Member] Loan to finance the purchase real estate. Document Information [Table] Farmland Loans [Member] Loan to finance the purchase of farm land. Total capital (to Risk- Weighted Assets), Ratio Total capital (to Risk- Weighted Assets), Adequately capitalized threshold, Ratio Entity Public Float Entity Filer Category Tier I capital (to Risk- Weighted Assets), Ratio Entity Current Reporting Status Tier I capital (to Risk- Weighted Assets), Adequately capitalized threshold, Ratio Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets Entity Voluntary Filers us-gaap_DividendsCommonStock Cash dividends declared Tier I capital (to Risk- Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio Entity Well-known Seasoned Issuer Total capital (to Risk- Weighted Assets), Amount us-gaap_IncreaseDecreaseInAccruedInterestReceivableNet Increase in interest receivable Total capital (to Risk- Weighted Assets), Adequately capitalized threshold, Amount Total capital (to Risk- Weighted Assets), To be well capitalized under prompt corrective action provisions, Amount us-gaap_AdjustmentsToAdditionalPaidInCapitalTaxEffectFromShareBasedCompensation Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Cash surrender value of life insurance Bank Owned Life Insurance Tier I capital (to Average Assets), Amount Tier I capital (to Average Assets), Adequately capitalized threshold, Amount Tier I capital (to Average Assets), To be well capitalized under prompt corrective action provisions, Amount Stock based compensation Statement of Comprehensive Income [Abstract] Entity Central Index Key Tier I capital (to Risk- Weighted Assets), Amount Entity Registrant Name Tier I capital (to Risk- Weighted Assets), Adequately capitalized threshold, Amount Tier I capital (to Risk- Weighted Assets), To be well capitalized under prompt corrective action provisions, Amount Entity [Domain] Legal Entity [Axis] Schedule of Compliance with Regulatory Capital Requirements under Banking Regulations [Table Text Block] Regulatory Capital Requirements under Banking Regulations [Text Block] Entity Common Stock, Shares Outstanding (in shares) Weighted average risk grade of loans Represents the weighted average risk grade for the loans. Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Change in Allowance for Loan Losses [Table Text Block] Changes in the allowance off balance sheet commitments. Reclassification from adoption of ASU 2016-01 The amount reclassified from accumulated other comprehensive income to retained earnings due to a change in reporting on securities. APIC reclassification The amount of reclassification of additional paid in capital to common stock during the period. us-gaap_AdvertisingExpense Advertising Expense ovly_NumberOfDebtSecuritiesAvailableforsaleSold Number of Debt Securities, Available-for-sale, Sold The number of available for sale debt securities sold during the period. Loans, net of allowance for loan loss of $8,685 and $8,166 at December 31, 2018 and 2017, respectively Loans Loans and Leases Receivable, Gross, Total us-gaap_LoansAndLeasesReceivableDeferredIncome Deferred loan fees and costs, net us-gaap_LoansAndLeasesReceivableAllowance Allowance for loan losses Beginning balance Ending balance Trading Symbol Entity Shell Company Data processing fees Occupancy expenses Stock options exercised (in shares) Exercised, Shares (in shares) us-gaap_TableTextBlock Notes Tables Restricted stock issued (in shares) Stock Issued During Period, Shares, Restricted Stock Award, Gross us-gaap_StockIssuedDuringPeriodSharesRestrictedStockAwardForfeited Restricted stock forfeited (in shares) Stock options exercised Restricted stock issued Related Party [Axis] Related Party [Domain] us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsGrantsInPeriodGross Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardOptionsForfeituresInPeriod Forfeited, Shares (in shares) us-gaap_OtherRealEstateOwnedMeasurementInput Other Real Estate Owned, Measurement Input Federal Home Loan Bank stock Federal Reserve Bank stock us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresAmountOfAvailableUnusedFunds Federal Home Loan Bank, Advances, General Debt Obligations, Amount of Available, Unused Funds Total liabilities and shareholders' equity us-gaap_FederalHomeLoanBankAdvancesGeneralDebtObligationsDisclosuresCollateralPledged1 Federal Home Loan Bank, Advances, General Debt Obligations, Disclosures, Collateral Pledged Reported Value Measurement [Member] Related Party Transaction [Axis] Related Party Transaction [Domain] Federal funds sold ovly_OtherPostretirementDefinedBenefitPlanExpectedAnnualFutureBenefitPaymentsPeriod Other Postretirement Defined Benefit Plan Expected Annual Future Benefit Payments Period Represents the period after retirement for which the participants under the plan will be provided with a fixed annual retirement benefit. Retained earnings Accumulated other comprehensive (loss) income, net of tax Director Retirement Plan [Member] Under the DRP, the participants will be provided with a fixed annual retirement benefit for ten years after retirement. The Bank is also responsible for certain pre-retirement death benefits under the DRP. Measurement Input, Discount Rate [Member] Debt Disclosure [Text Block] us-gaap_InterestExpense Total interest expense us-gaap_DisclosureTextBlockAbstract Notes to Financial Statements ovly_ConversionOfStockSharesConvertedForEachOutstandingShareOfWhollyOwnedSubsidiary Conversion of Stock Shares Converted for Each Outstanding Share of Wholly Owned Subsidiary Represents the number of shares of the entity converted for each outstanding share of wholly-owned subsidiary. ovly_NumberOfFormsOfOutstandingStockAwards Number of Forms of Outstanding Stock Awards Represents the number of forms of outstanding stock awards available with the entity. Other time deposits Goodwill and other intangible assets, net Federal Reserve Bank Stock, Policy [Policy Text Block] Reserve Bank stock represents an equity interest in the Federal Reserve Bank. It does not have a readily determinable fair value because its ownership is restricted and it lacks a market (liquidity). Cash and Cash Equivalents Disclosure [Text Block] Pension and Other Postretirement Benefits Disclosure [Text Block] Federal Home Loan Bank Stock, Policy [Policy Text Block] Disclosure of accounting policy on federal home loan bank stock. ovly_ImpairedLoansFairValueDisclosure Impaired loans This element represents the fair value of impaired loans at period-end. This element is intended to be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. us-gaap_IncomeLossFromEquityMethodInvestmentsNetOfDividendsOrDistributions Undistributed net income of subsidiary Property Plant and Equipment Estimated Useful Lives [Table Text Block] Tabular disclosure of estimated useful lives of premises and equipment. ovly_NumberOfFormsOfOutstandingCommonStock Number Of Forms Of Outstanding Common Stock Represents the number of forms of outstanding stock awards available with the entity. (Increase) decrease in deferred tax asset Deferred Measurement Input Type [Axis] us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseAfterYearFive Thereafter Measurement Input Type [Domain] Employee benefit expense Measurement Input, Appraised Value [Member] Fair Value Measurement, Policy [Policy Text Block] us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearTwo 2020 us-gaap_InterestExpenseDeposits Deposits Fair Value of Financial Instruments, Policy [Policy Text Block] us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearThree 2021 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFour 2022 us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseYearFive 2023 Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Non-vested restricted stock, Weighted avg shares (in shares) Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of non-vested restricted shares. Subsequent Events, Policy [Policy Text Block] us-gaap_FiniteLivedIntangibleAssetsAmortizationExpenseNextTwelveMonths 2019 Stock options, Weighted avg shares (in shares) Additional shares included in the calculation of diluted EPS as a result of the potentially dilutive effect of stock options. SEC Schedule, 12-09, Valuation Allowances and Reserves [Domain] us-gaap_ShareBasedCompensation Stock based compensation SEC Schedule, 12-09, Valuation Allowances and Reserves Type [Axis] us-gaap_FiniteLivedIntangibleAssetUsefulLife Finite-Lived Intangible Asset, Useful Life Earnings Per Share, Policy [Policy Text Block] INTEREST EXPENSE Amortization of investment securities, net Comprehensive Income, Policy [Policy Text Block] Schedule of Deposit Account Balances [Table Text Block] Schedule of deposit account balances. Income Tax, Policy [Policy Text Block] Total income Total interest income Schedule of Maturities of Deposit [Table Text Block] Tabular disclosure of certificates of deposit issued and their remaining maturities. Interest on deposits with banks Time deposits $250,000 and under The aggregate amount of domestic or foreign time deposits (including certificates of deposits, individual retirement accounts and open accounts) that total to $250,000 and under. ovly_TimeDepositsMoreThan250000 Time deposits over $250,000 The aggregate amount of domestic and foreign time deposit liabilities (including certificates of deposits, individual retirement accounts and open accounts) in denominations of more than $250,000 Savings and other deposits Represents the interest expense incurred on savings and other deposits. Time deposits over $250,000 Interest expense incurred on time deposits, including certificates of deposits, more than $250,000 in domestic offices. Interest on federal funds sold Depreciation Depreciation, Total OREO expenses Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from other real estate owned expenses. Interest on securities ovly_DeferredTaxLiabilitiesAccruedBonus Accrued bonus Amount of deferred tax liability attributable to taxable temporary differences from accrued bonus. ovly_DeferredTaxLiabilitiesUnrealizedGainsOnSecuritiesAvailableForSale Unrealized gain on securities available for sale Amount of deferred tax liability attributable to taxable temporary differences from unrealized gains on securities available for sale. Holding company organization fees Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from organization fees. ovly_DeferredTaxLiabilitiesFHLBDividends FHLB dividends Amount of deferred tax liability attributable to taxable temporary differences from Federal Home Loan Bank dividends. us-gaap_CashAndCashEquivalentsFairValueDisclosure Cash and cash equivalents Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] us-gaap_TimeDepositMaturitiesYearFour 2022 us-gaap_TimeDepositMaturitiesYearFive 2023 us-gaap_TimeDepositMaturitiesYearOne 2019 us-gaap_ImpairmentOfIntangibleAssetsExcludingGoodwill Impairment of Intangible Assets (Excluding Goodwill), Total us-gaap_TimeDepositMaturitiesYearTwo 2020 us-gaap_TimeDepositMaturitiesYearThree 2021 Fair Value, Measurements, Nonrecurring [Member] Advertising Costs, Policy [Policy Text Block] Common stock, no par value; 50,000,000 shares authorized, 8,194,805 and 8,098,605 shares issued and outstanding at December 31, 2018 and 2017, respectively Adjustments to reconcile net income to net cash from operating activities: Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Interest and fees on loans Fair Value, Measurements, Recurring [Member] Common stock, shares authorized (in shares) Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block] Common stock, shares issued (in shares) Fair Value Measurements, Recurring and Nonrecurring [Table Text Block] Common stock, par value (in dollars per share) Range [Domain] Maximum [Member] Minimum [Member] Weighted Average [Member] ovly_ShareBasedCompensationArrangementsByShareBasedPaymentAwardNumberOfPlans Share-based Compensation Arrangements by Share-based Payment Award, Number of Plans Represents the number of equity based incentive plans under the share-based arrangements. Product and Service [Axis] Product and Service [Domain] Range [Axis] INTEREST INCOME Net deferred tax asset Net deferred income tax asset Interest Checking Reserve [Member] Represents information about checking reserve. Property, Plant and Equipment Disclosure [Text Block] Equity Line [Member] Represents information about equity line. Goodwill and Intangible Assets, Policy [Policy Text Block] Property, Plant and Equipment [Table Text Block] us-gaap_DeferredTaxAssetsGross us-gaap_DeferredIncomeTaxLiabilities Undisbursed Loan Commitments [Member] Represents information about undisbursed loan commitments. 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State income tax Fair Value Hierarchy and NAV [Axis] Construction, Renovation and Design Work [Member] Represents information about construction, renovation and design work performed in connection with various projects and maintenance on the Bank's branches. Provision for loan losses us-gaap_InterestIncomeExpenseAfterProvisionForLoanLoss Net interest income after provision for loan losses Profit Sharing Plan [Text Block] The entire disclosure for profit sharing plan. 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Common Equity Tier 1 Capital (to Risk Weighted Assets), To be well capitalized under prompt corrective action provisions, Ratio The common equity tier 1 risk based capital ratio (common equity tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized", in the regulatory framework for prompt corrective action. us-gaap_DeferredTaxLiabilitiesFinancingArrangements Deferred loan costs Parent Company [Member] us-gaap_DeferredTaxLiabilitiesInvestmentInNoncontrolledAffiliates Limited partner investment in small business equity fund Marketable Securities, Policy [Policy Text Block] Consolidated Entities [Axis] Consolidated Entities [Domain] Type of Adoption [Domain] Related allowance us-gaap_DeferredTaxLiabilitiesPropertyPlantAndEquipment Accumulated depreciation us-gaap_DeferredTaxLiabilitiesPrepaidExpenses Prepaid expenses Adjustments for New Accounting Pronouncements [Axis] us-gaap_ImpairedFinancingReceivableInterestIncomeAccrualMethod Impaired Financing Receivable, Interest Income, Accrual Method, Total Condensed Cash Flow Statement [Table Text Block] Condensed Balance Sheet [Table Text Block] Condensed Income Statement [Table Text Block] Recorded investment with no allowance us-gaap_PaymentsOfDividendsCommonStock Shareholder cash dividends paid Recorded investment with allowance Total recorded investment Change in contributions payable to LIHTC limited partner investment The amount of change in contributions payable to Limited Partner Investment. 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